1. Field of the Invention
The present invention relates to a novel polymer and cement admixture comprising the same.
2. Description of the Related Art
A cement admixture is usually added to a cement composition (including, cement paste prepared by adding water thereinto, mortar prepared by mixing sand as fine aggregate thereinto, and concrete prepared by mixing pebble as coarse aggregate thereinto) for enhancing the durability and strength by reducing of the unit quantity of water. A cement admixture also has function of preventing cement particles from being agglutinated by absorbed to the cement particles and enhancing the dispersibility of the cement composition in use.
As a cement admixture, for instance, naphthalene series and polycarboxylic acid series are known. The Japanese Patent Application Laid-Open No. 2001-220417, for instance, discloses that a copolymer used for cement admixtures, prepared by copolymerization of an unsaturated carboxylic monomer and an unsaturated polyalkylene glycol monomer.
This copolymer, used for cement admixtures, including a carboxylic group derived from an unsaturated carboxylic monomer can act as an absorbing group which is absorbed to the cement particles, and a polyalkylene glycol chain derived from an unsaturated polyalkylene glycol ether series monomer can act as a dispersing group which disperses the cement particles.
However, a copolymer used for cement admixtures such as the one disclosed in the Japanese Patent Application Laid-Open No. 2001-220417, can be a cement admixture exhibiting certain dispersing ability by means of the steric repulsion of the polyalkylene glycol chain derived from the unsaturated polyalkylene glycol ether series monomer. In addition, it is required that the development of cement admixtures which can exhibit further higher dispersing abilities in order to reduce the quantity of cement admixtures.
On the other hand, in Wako Technical Bulletin, “Polymeric azo initiators—VPS series and VPE series—”, published by Wako Pure Chemical Industries, Ltd., polymeric azo initiators, having polyethylene glycol chains, and block copolymers consisting of polyethylene glycol chain unit and methyl methacrylate or styrene unit, are disclosed and explained.
Furthermore, in “Block Copolymers Derived from Azobiscyanopentanoic Acid. VI. Synthesis of a Polyethylene glycol-Polystyrene Block Copolymer”, J. Polym. Sci.: Part A,: Polymer Chemistry, (U.S.A.) published by John Wiley & Sons, Inc, on page 405-418, vol. 24 in 1986, Akira Ueda et al., and “Block Copolymerization Initiated with a Polyethylene Glycol Containing Scissile Azo Linkages in Its Main Chain”, J. Polym. Sci.: Part A: Polymer Chemistry, (U.S.A.), published by John Wiley & Sons, Inc, on page 3495-3498, vol. 25, 1987, Akira Ueda et al., a production method of polymeric azo initiators with polyethylene glycol are disclosed and explained block copolymers consisting of polyethylene glycol chains and styrene, methyl methacrylate, methyl acrylate, vinyl acetate, or acrylonitrile.